Gene organization and bioinformatic analyses of DefSm1D, a defensin-like protein domain from flowers of Silybum marianum.

AGUSTINA FERNÁNDEZ; MARIA LAURA COLOMBO; SANDRA ELIZABETH VAIRO CAVALLI; CONSTANZA LIGGIERI; LAURA SUSANA BAKÁS

San Miguel de Tucumán

Congreso; III Latin American Federation of Biophysical Societies (LAFeBS) ? IX IberoAmerican Congress of Biophysics ? XLV Reunion Anual SAB 2016; 2016

Sociedad Argentina de Biofísica

Plant defensins and defensin-like (DEFL) proteins are small cationic, cysteine-richproteins ubiquitously expressed in the plant kingdom and mostly involved inhost defence. We have previously cloned, predict the structure and identifiedthe putative function of a DEFL from S.marianum flowers (DefSm1D), which revealed a potential antifungal effect.The aims ofthis this work were to find promotor motifs of the gene encoding DefSm1 andperform a bioinformatic analysis concerning electrostatic potential of theprotein surface in order to confirm our previous results on function-structure ofDefSm1D. To studyDefSm1 gene, a BLAST similarity search was performed using the shotgun sequenceof S. marianum whole genome asdatabase and DefSm1 sequence as query. The promoter analysis revealed thepresence of TATA box and the initiator element with appropriate spacing betweenthem for the synergistic effect that would increase promotor strength. Otherregulatory elements were identified using Plant Care all related with bioticstress response (CGTCA-motif involved in the methyl jasmonate responsiveness,TC-rich repeat involved in defence and stress response, elements involved insalicylic and abscisic acid responsiveness). The DefSm1 gene structure, asexpected, presented two exons with an intron positioned between the signalpeptide and mature protein. The presence of a peptide signal suggests aputative extracellular localization for DefSm1D, which would be consistent withits role in defence.Electrostaticsurface potential of DefSm1D was calculated solving the Poisson-Boltzmannequation through PBEQ-Solver. The surface charge distribution of DefSm1D endowsthe peptide with amphipathicity, which would allow it to interact with the cellmembrane of pathogens and exert its antimicrobial activity. Bothanalyses, at gene and protein level, confirm our previous results of DefSm1Drole in biotic stress.